This invention is in the field of oil and gas drilling and has a common, although not exclusive, application in off shore drilling where horizontal wells are involved.
It is recognised in the art of oil and gas drilling that it is, at times, desirable to provide annular isolation in a well liner using formation packers in lieu of conventional annular cementing. This allows for improved well management, and more specifically, the creation of zones to enable:
the separation of phases of oil, gas or water, in a well; PA1 the injection of chemicals, cement or the like at a particular predetermined location in the well; and or PA1 the monitoring or analysis of flow or other conditions at a particular location in the well. PA1 a) filling a compartment in or associated with a work string or liner string with cement or other settable fluid at or near the surface of the well; PA1 b) thereafter transporting the cement or settable fluid down the well bore in conjunction with the work string or liner string; and PA1 c) injecting the cement or other settable fluid into an inflatable packer. PA1 locating dedicated inflation tools on a string prior to running the string, the tools being separated by a distance corresponding to the distance separating the packers to be set; PA1 subsequently running the string, thereby transporting the inflation tools to the vicinity of the packers; PA1 aligning the inflation tools with the packers; and PA1 thereafter injecting fluid into the packers simultaneously.
Typically, packers used for the creation of such annular isolation or zones are of the inflatable type, adapted to be filled with cement or some other settable composition such as resin. Occasionally, the packers may be inflated with drilling mud, particularly if their use is only needed for a short time. The present invention results from a desire to provide improved and more reliable means of inflating these packers.
Inflatable packers may also be used in certain situations on the outside of the liner. The present invention also encompasses the inflation of packers in such location. Indeed, the invention may be applied to any situation or location where down hole packers require to be inflated.
Where cement or other settable fluid has been used in the past, the task of inflating a packer required pumping a relatively small amount of the settable fluid from the surface to a remote location where a packer is to be set, potentially tens of thousands of feet from the surface. The cement or other composition has been required to be pumped to the precise location of the packer or each packer to be inflated. This involved several procedural steps, with the success of the entire procedure being dependent on each step being performed successfully
In many cases, it is important also for the cement or other settable composition to be delivered to the packer without having been contaminated by other fluids, such as mud or the like. Again this has proved difficult to achieve in the past, leading to eventual packer failure as a result of it being inflated with cement or other composition of low integrity.